text: Hydroxyl radicals can occasionally be produced as a byproduct of Immune action. Macrophages and Microglia most frequently generate this compound when exposed to very specific pathogens, such as certain bacteria. The destructive action of Hydroxyl Radicals has been implicated in several neurological autoimmune diseases such as HAND when immune cells become over-activated and toxic to neighboring healthy cells.
  The hydroxyl radical can damage virtually all types of macromolecules: carbohydrates, nucleic acids (mutations), lipids (lipid peroxidation) and amino acids (e.g. conversion of Phe to m-Tyrosine and o-Tyrosine).  PMID 7776173. The hydroxyl radical has a very short in vivo half-life of approximately 10 seconds and a high reactivity. This makes it a very dangerous compound to the organism.
  Unlike superoxide, which can be detoxified by superoxide dismutase, the hydroxyl radical cannot be eliminated by an enzymatic reaction. Mechanisms for scavenging peroxyl radicals for the protection of cellular structures includes endogenous antioxidants such as melatonin and glutathione, and dietary antioxidants such as mannitol and vitamin E.